Notes, summaries, assignments, exams, and problems for Biology

Staphylococcus

• Easily develops antimicrobial resistance
• Gram-positive cocci
• Catalase-positive
• Facultative anaerobes
• Not demanding in their nutritional requirements
• Grow in normal media
• Some pathogenic species are generally opportunistic pathogens, commensals
• Important in animal and human infections

Natural Habitat

Widespread in nature; found on human and animal skin, surfaces of objects, air, soil, water, and milk.

S. aureus

Main pathogen associated with infections; colonizes nasal passages and pharynx.

S. epidermidis

Produces skin lesions, wound infections; microbiota found in the skin, respiratory tract, and gastrointestinal tract.

S. saprophyticus

Associated with urinary tract infections.

Immunogens

• Polysaccharide A (specific for S. aureus)
  • Antiphagocytic
  • Antiplatelet
  • Activator

The Nervous System

Consisting of two types of cells:

• Neurons: consist of neuronal bodies, Dendrites (extensions where the nerve impulse enters the body), and axons.
• Glia (or Neuroglia): Made by the supporting structure of the nervous system, they collaborate in nutrition and feeding of neurons.

Nervous System Division

Central Nervous System (CNS), peripheral nervous system, autonomic (or vegetative) nervous system.

Central Nervous System

Comprising:

• Brain: Located in the skull, it consists of an internal gray substance and an external white substance. Surrounded by 3 membranes called meninges: Piamater, Arachnoid, Dura mater.

Parts:

• Cerebrum: Divided into hemispheres (left and right), weighing between 1200 and 1600g. It includes frontal, parietal, occipital,

Lung Cancer Impact: Eastern Europe and North America have the highest lung cancer incidence rates. Men are disproportionately affected, with rates 76% higher in men than in women in Eastern Europe and 69% higher in North America. However, incidence in women is increasing. The 5-year survival rate remains very low.

Risk Factors: Smoking accounts for a substantial portion of lung cancer deaths: 80% in men, 75% in women, and contributes to 17% of lung cancer cases in non-smokers. Smoking is also linked to 28% of all cancer deaths. Other risk factors include asbestos, radon exposure (mining or environmental), a diet low in vitamins A, C, E, and beta-carotene, as well as genetic and familial factors.

Lung Cancer Control: Effective control strategies... Continue reading "Lung Cancer: Incidence, Risks, and Diagnosis" »

Understanding Health and Well-being

Health is a state of complete physical, mental, and social well-being, and not merely the absence of disease.

Health depends on individual lifestyle and personal behavior, including physical activity, environmental and social factors such as climate and pollution, and genetic information.

Myocardial Infarction (Heart Attack)

When blood flow through a vessel of the heart is blocked, blood stops flowing to an area of heart muscle, halting the supply of oxygen and nutrients. This leads to muscle tissue death and permanent heart damage. If the blockage is partial and reduces blood flow, it causes a sharp pain known as angina.

Symptoms of a Heart Attack

Symptoms start with pain or discomfort in the center of the chest,... Continue reading "Understanding Health, Heart Attacks, and Risk Factors" »

How Infectious Diseases Spread

Infectious diseases can spread through various means:

• Water: Consuming water contaminated with feces from humans or animals.
• Food: Eating fruits and vegetables irrigated with contaminated water or improper food handling.
• Animals: Through disease vectors. For example, the Anopheles mosquito transmits malaria.

Stages of Infectious Disease Development

The development of infectious diseases involves several stages:

• Infection: The organism enters the body.
• Incubation Period: The time from infection to the appearance of symptoms.
• Period of Manifestation: The disease is fully manifested, with symptoms like fever and pain.
• Period of Decline: Symptoms subside due to the immune system and medications.
• Convalescence: The patient recovers

Understanding Circulation and Blood Disorders

Pulmonary and Systemic Circulation

Pulmonary Circulation: Circulation through the lungs.

Systemic Circulation: Circulation to the rest of the body.

Vena Cava: Carries deoxygenated blood.

Coronary Heart Disease

Coronary Heart Disease: Refers to any disease that results in blockage of the coronary blood supply to part of the heart's muscular wall. The blockage causes partial deprivation of oxygen to the affected part and may result in the death of muscle cells.

Effects of Coronary Heart Disease

If a large part of the heart is affected, the person may die instantly. If a small region is affected, it may recuperate.

Atherosclerosis

Atherosclerosis: The most common form of hardening of the arteries. It begins... Continue reading "Understanding Pulmonary and Systemic Circulation & Blood Disorders" »

Occupational Hazards

Hearing Loss

Occupational hearing loss, or deafness, is the functional deficit that occurs when an individual experiences a partial or complete loss of hearing. This is determined by the hearing threshold, which is the weakest sound stimulus that a particular ear can perceive. While the terms "deafness" and "hearing loss" are often used interchangeably, they are distinct conditions.

Pneumoconiosis

Pneumoconiosis encompasses a group of lung diseases caused by inhaling and accumulating inorganic dust particles, and the subsequent reaction within lung tissue. Disease development depends on the dose of inhaled and retained particles, the particles' biological activity, the induced tissue reaction, and individual sensitivity.

Drug

Mitosis: Cell Division for Growth

1. Interphase: DNA and centrosomes have been duplicated.
2. Prophase: The nuclear membrane disappears, chromosomes condense and become visible, and the spindle apparatus begins to form from proteins.
3. Metaphase: The centrioles are at opposite poles of the cell. The spindle fibers align the chromosomes at the cell's equator (metaphase plate).
4. Anaphase: The spindle fibers pull the sister chromatids of each chromosome toward opposite centrosomes.
5. Telophase: The chromatids decondense back into chromatin. New nuclear membranes form around the chromatin, and the spindle breaks down.
6. Cytokinesis: The cytoplasm is divided, forming two new, genetically identical daughter cells.

Meiosis: Producing Gametes

Interphase: DNA and centrosomes... Continue reading "Mitosis vs Meiosis: Understanding Cell Division Processes" »

What is Animal Cloning?

Cloning is the process by which we obtain an identical copy, or clone, from the genetic point of view of any living entity, such as a cell or an organism.

How Do You Clone an Animal?

The first time that clone cells were obtained from an adult animal was in 1996. As a result, the sheep Dolly was born, the first mammal cloned in history. The technique used is called nuclear transfer.

Stages of Animal Cloning

1. A differentiated cell is taken from the individual that is to be cloned. These cells contain the entire genome of the organism, with the difference that it is a specialized cell that has lost the ability to reproduce.
2. An egg is taken from a female donor.
3. The egg nucleus is removed.
4. The nucleus of the differentiated cell is

Sensory Perception and Bodily Responses

Sensory Perception

Sensory perception is the process of obtaining information through our senses: sight, hearing, balance, smell, taste, and touch. Receptors also exist that capture the internal conditions within the body.

Bodily Responses

Our body's responses are executed by the locomotor system (formed by bones and muscles) and the endocrine system (which functions through hormones), responsible for movement and regulation.

The Sense of Sight (Vision)

Key components of the eye include:

• Cornea: A transparent layer that covers the front of the eye.
• Iris: A layer that can dilate or shrink, regulating the passage of light through an opening called the pupil.
• Sclera: The layer that gives shape to the eyeball.
• Conjunctiva: